I need the steps and answers please

Answer:
For problem 15 it's y=15/4-7x
For problem 13 it's x=31-5y/6
Step-by-step explanation:
Problem 15:
y(4-7x)=15
y=15/4-7x
Problem 13:
6x=31-5y
x=31-5y/6
Answer:
13) Ans;
[tex]6x + 5y = 31 \\ 6x = 31 - 5y \\ \\ x = \frac{31 - 5y}{6} \\ \\ x = \frac{31}{6} - \frac{5y}{6} [/tex]
15)Ans;
[tex]4y - 7xy = 15 \\ y(4 - 7x) = 15 \\ \\ y = \frac{15}{4 - 7x} [/tex]
I hope I helped you^_^