How to use computed in vue to realize the addition of two input values to another input value in real time

basic salary + performance pay = payable salary
payable salary-Social Security deduction = actual salary
is a way to look like a rookie, please give me some advice.
Please be as detailed as possible

related codes

/ / Please paste the code text below (do not replace the code with pictures)

<Form  :label-width="100" :model="popp" :mode="mode">
          <div v-width="500" v-height="400">
            <FormItem label="" prop="name" >
              <input type="text" v-model="popp.name" :disabled="true">
            </FormItem>
            <FormItem label="" prop="department">
              <input type="text" v-model="popp.department" :disabled="true">
            </FormItem>
            <FormItem label="" prop="duty">
              <input type="text" v-model="popp.duty" >
            </FormItem>
            <FormItem label="" prop="basic" >
              <input type="number" step="0.1" v-model="popp.basic" >
            </FormItem>
            <FormItem label="" prop="perf"  >
              <input type="number" step="0.1" v-model="popp.perf" >
            </FormItem>
            <FormItem label="" prop="social">
              <input type="number" step="0.1" v-model="popp.social" >
            </FormItem>
            <FormItem label="" prop="should" >
              <input type="number" step="0.1" v-model="popp.should" @input="a1"  >
            </FormItem>
            <FormItem label="" prop="actual" >
              <input type="number" step="0.1" v-model="popp.actual" @input="a2" >
            </FormItem>
            <FormItem label="" prop="remark">
              <input type="text" v-model="popp.remark" >
            </FormItem>
          </div>
          <div style="text-align:center;">
            <button class="h-btn"  @click="submit"></button>
            <button class="h-btn" @click="crose"></button>
          </div>
        </Form>

what result do you expect? What is the error message actually seen?

Vue.js

Jun.06,2022

<div class="form"> <form action=""> <div> <label for=""></label> <input type="text" v-model="popp.basic"> </div> <div> <label for=""></label> <input type="text" v-model="popp.perf"> </div> <div> <label for=""></label> <input type="text" v-model="should"> </div> </form> </div>

data () { return { popp: { basic: 2200, perf: 1000 } } }, computed: { should () { return parseInt(this.popp.basic) + parseInt(this.popp.perf) } },