.text
.org 0x20

stev1:  .word 0x50
stev2:  .word 100
stev3:  .word 0x2f

.align

.global _start
_start:

  adr r0, stev3
  ldr r3, [r0]

  adr r0, stev2
  ldr r2, [r0]

  adr r0, stev1
  ldr r1, [r0]

  add r2, r3
  sub r1, r2, r1

  str r1, [r0]