Answer:

Step-by-step explanation:
You answer is 3 and here's why...
7x + 5 - 3x - 7 = 10
First you must collect like terms
And that gives us
4x - 2 = 10
Next you must simplify by removing additives
4x - 2 + 2 = 10 + 2
4x = 12
Now you must divide
4x/4 = 12/4
x = 3
Answer:
x+3y+z=21
Step-by-step explanation:
x+3y+z
4+3(5)+2
4+15+2
21