.5 cups is equal to 1/2 cup.
Half of 1 cup equals 4 fluid ounces.
Bring like terms together
(REMEMBER CHANGE THE SIGN WHEN MOVING ACROSS THE EQUAL SIGN i.e. - becomes + and + becomes -)
4x - 2x = 7 - 3
2x = 4
divide both sides by 2
x = 2
Not sure if you are just looking for equations but it would be written as
1/4(r+10)=r-4
Solving would be
1/4r+10/4=r-4
26/4=3/4r
r=26/3 or 8.66