math
posted by Anonymous .
F+7=10

so, what number do you have to add to 7 to get 10?

Subtract 7 from both sides.
F+7=10
F = 3 
10  7 = 3. All you have to do is take the number that is IN the equation (do the opposite operation than what it says) and (for this one) subtract it by the number that the equation is equal to.