What is a negative minus another negative i can't seem to find out. i have a question that says-3.7 - (-4.9) and the calculator says 1.2 but i think thats wrong.

Andrea went to the store to buy sweater that was on sale for 40% off the original price it was then put on clearance an additional 25% off the sale price she also use a coupon that saved her an additional five dollars and j did not spend more than $7.60 for the sweater what are the possible values for the original price of the sweater?

Kylie explained that (-4x+9)^2 will result in a difference of squares because (-4x+9)^2 (-4x+9)^2 =(-4x)^2+(9)^2=16x^2+81

What are the measures of ∠a, ∠b, ∠c and ∠d? explain how to find each of the angle measure.