Question

how do i solve 7r+22k=101 8r+20k=100

Answer 1

Solve by substitution/elimination, have you tried it?

Answer 2

7r+22k=101
8r+20k=100

is called a "system of linear equations."

You could solve either equation for r and substitute the result into the other equation, for r. That's the substitution method.

Or, you could solve this system by elimination through addition/subtraction. Try this:
Multiply the first equation by 8; multiply the second equation by -7.
Combine the two resulting equations.