5×10⁶+7×10⁴
how do you solve this?

5×10⁶+7×10⁴
you have to follow PEMDAS (parentheses, exponents, multiplication, division, addition and subtraction)
so first you would solve the exponents since there is no parentheses  (10⁶ and 10⁴) so you would end up with 
5x1000000+7x10000
then you multiply 5x1000000 and you would end up with 
5000000

5000000+7x10000
multiply 7x10000 and that would give you
70000

5000000+70000
your answer is 5070000

The total time is 6+0.5+2 which is 8.5, and Aileen spent 6 hours in classes. So the percentage is gonna be 6/8.5 x 100 which is 70.5 percent.