Ashley's pencil holder is 12 cubes long, 4 cubes wide and 5 cubes high. It is only 1 cube thick everywhere. How many cubes did she use for the pencil holder?

Find the sum of 4x^{2} -4+6 and -7^{2} +3x+1

If 1/√5+1/√5+1=p+q√r , find the values of p, q and r

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.