a) 21 + 6 = 27
b) 7 * 3 = 21
c) 2 * (3 + 3) = 12
d) 3 * 7 + 4 = 25
e) 2 + 2 * 8 = 10 + 8
f) 3 * 5 - 7 = 3 + 5
a + 6 = 27
a = 27 - 6
a = 21
7b = 21
b = 21/7
b = 3
2 * (c + 3) = 12
2c + 6 = 12
2c = 12 - 6
2c = 6
c = 6/2
c = 3
3d + 4 = 25
3d = 25 - 4
3d = 21
d = 21/3
d = 7
2 + 2f = 10 + f
2f - f = 10 - 2
f = 8
3g - 7 = 3 + g
3g - 1 = 3 + 7
2g = 10
g = 10/2
g = 5
