Question

Afla doua numere stiind ca suma lor este 55, diferenta este 15

Answer 1

a+b=55 ⇔  a=55-b
a-b=15

55-b-b=15                       
55-2b=15
-2b=15-55
-2b=-40
b=20

a-20=15
a=15+20
a=35

Answer 2

a+b=55
a-b=15

a=b+15
b+15+b=55
2×b+15=55
2×b=55-15
2×b=40
b=40:2
b=20

a=b+15
a=20+15
a=35

verificare
35+20=55
35-20=15