Plz I need help with my math hw

What number should be added to both sides of the equation to complete this square? x^2-10x=7

In triangle opq right angled at p op=7cm, oq-pq=1 determine the values of sinq and cosq

Astudent must have an average on five test that is greater than it equal to 80% but less than 90% to receive a final grade of b. devon's greades on the first four test were 78% 62% 91% and 80% what range if grades on the fifth test would give him a b in the course? ( assuming the highest grade is 100%)