Страница 87номер 7 3*(6+a)=45. 12-40: k=4. (30-n): 2=9 7*b-15=6. 20: (x: 9)=4. (9*t+37): 8=8

73(6+a)=45
438+73a=45
73a=45 - 438
73a= - 393
a= - 393 : 73
a= - 5 28/73

12 - 40:k=4
40: k= 12 -4
40 : k= 8
k = 40 : 8
k= 5

(30-n):2=9
30- n = 9*2
30 -n= 18
n = 30 -18
n= 12

7b-15=6
7b=6+15
7b=21
b=21:7
b=3

20 :(x:9)=4
x:9= 20:4
x:9=5
x=9*5
x=45

(9t+37):8=8
9t+37=8*8
9t+37=64
9t=64 - 37
9t=27
t=27:9
t=3