3x+5=41

y + (y+7) + (y+7-8) = 81

n + (n-8) = n+15

m + (m+7) = (m-7) + 10

1) 3 х+5=41

3 х=41-5

3 х=36

х=36:3

х=12

2) у + (у+7) + (у+7-8) = 81

у+у+7+у+7-8=81

3 у+6=81

3 у=81-6

3 у=75

у=75:3

у=25

3) n + (n-8) = n+15

n+n-8=n+15

n+n-n=15+8

n=23

4) m + (m+7) = (m-7) + 10

m+m+7=m-7+10

m+m-m=-7+10-7

m=-4