Question

Afla termenul necunoscut:3×5+a=7×9; 7×6+a=9×8; 900-a=7×4; 320-a=9×5×2; a-4×5=7×2; a-8×2=7×5×4.

Answer 1

1) 15 + a = 63
a = 63-15
a = 48
2) 42 + a = 72
a = 72-42
a= 30
3) 900 - a = 28
a = 872
4) 320 - a = 90
a = 230
5) a - 20 = 14
a = 34
6) a - 16 = 140
a = 156

Answer 2

3*5+a=7*9
15+a=63
a=63-15
a=48

7*6+a=9*8
42+a=72
a=72-42
a=30

900-a=7*4
900-a=28
a=900-28
a=872

320-a=9*5*2
320-a=90
a=320-90
a=230

a-4*5=7*2
a-20=14
a=14+20
a=34

a-8*2=7*5*4
a-16=35*4
a-16=140
a=140+16
a=156