Question

Given the equations y=c+3 and d=x+7, which of the following is equivalent to x + y written in terms of c and d?
I solved it both ways and firstly I've got:
Y=c+3, x=d-7
C+3+d-7 = C+D-4 correct answer
But on the second try I've got: X+y= C+3+7-d C+10-D incorrect
How should I solve this equation to get the correct answer? What is the rule?

Answer 1

Answer:

d+c-4

Step-by-step explanation:

In second try, you have written (-d) instead of (+d) and (+7) instead of (-7).

That is the reason for wrong answer.

Refer the photo