Answer:
Since there is alot here I will answer a few so that you can apply the same logic to the others
Substitute the values into each equation and simplify
19. 4xy
X = 1 and Y = 3
4 * 1 * 3 = 12
25. 4yz - 8xy
X = 1, Y = 3 and Z = 4
4 * 3 * 4 - 8 * 1 * 3
48 - 24 = 24
31. 3p(2q + r)
p = 2, q = 1 and r = 3
3 * 2 (2 * 1 + 3)
6 (2 + 3)
12 + 18 = 30
38. 3qr + p(2q + r)
p = 2, q = 1 and r = 3
3 * 1 * 3 + 2(2 * 1 + 3)
9 + 2(2 + 3)
9 + 4 + 6 = 19
Feel free to comment if you need more explanation
