5) BRAINLIEST AND 10+ POINTS! :)

Answer:
b) 1000x + 115
Step-by-step explanation:
C = 20y + 15
= 20(50x + 5) + 15
= 1000x + 100 + 15
= 1000x + 115
Answer:
B
Step-by-step explanation:
We see that C = 20y + 15 and that y = 50x + 5, so let's actually substitute the expression 50x + 5 in for y in the first equation:
C = 20y + 15 = 20 * (50x + 5) + 15
Now, simply distribute the 20:
20 * (50x + 5) + 15 = 20 * 50x + 20 * 5 + 15 = 1000x + 100 + 15 = 1000x + 115
Thus, C in terms of x is C = 1000x + 115, or B.
Hope this helps!