9.725 would be the answer
There are 49 gallons of red paint.
I figured it out by doing the following:

If you subtract the gallons of pink paint (21) from the total number of gallons (70), then you get the number of gallons of red paint (49) because 49 + 21 = 70. I hope that helps :)
Options a and b are the algebraic expressions
it would be 100.01% That is because in a percentage you have to move the decimal point two places to the right.