The second angle of a triangle is 3 times as large as the first angle. The thrid angle is 30 degrees more than the first angle. Find the measures for the angles.

Fractions can be added and subtracted only if they're fractions. a. like b. proper c. improper d. unlike

Which one ? is the answer and how to find this answer

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?