To calculate $51^2$, Alex mentally figures the value $50^2$ and adds 101. Alex subtracts a number from $50^2$ to calculate $48^2$. What number does she subtract?

The ratio of rock songs to dance songs on jonathan’s mp3 player is 5: 6. the total number of rock and dance songs jonathan has is between 101 120. how many rock songs does he have?

*let m∠cob = 50°30’, m∠aob = 70° and m∠aoc = 20°30’. could point c be in the interior of ∠aob? why?

Asmall book publisher knows that 26 books weigh 41 lbs. how much do 40 books weigh?