Question

Please help will give medal! :D

Evaluate 2a + 3b, when a = 4 and b = 3.
A. 12
B. 17
C. 57
D. 60

Answer 1

wherever you see an 'a', replace it with 4 because a = 4

Answer 2

same thing with b, but replace every copy of b with 3 since b = 3

Answer 3

2a + 3b

2*4 + 3b ... replace every 'a' with 4

2*4 + 3*3 ... replace every 'b' with 3

8 + 9

17


So 2a + 3b = 17 when a = 4 and b = 3. Not so bad right? Hopefully it clicks a bit better. You should practice on this concept because it is a major building block in algebra and pretty much any field that uses math.