Question

a+b=17,4 a=b-21 a=? b=?

Answer 1

$a + b = 17.4$

$a = b - 21$

$b - 21 + b = 17.4$

$b + b = 17.4 + 21$

$2b = 38.4$

$b = \frac{38.4}{2}$

$b = 19.2$

$a = b - 21$

$a = 19.2 - 21$

$a = - 1.8$

Answer 2

a+b =17.4
a =b-21

b-21 +b =17.4
2b =17.4+21
2b =38.4
b =19.2
a =19.2 -21 = -1.8