Well try working on the problem first
1.) The sum(addition) of 21 and 5 times(multiplication) a number f is(=) 61.
f = unknown number/variable [So 21 plus 5f(5 times f) equals 61]
21 + 5f = 61 [21(one-time) + 5f(number x variable) = 61(total)]
2.) Seventeen more(addition) than seven times(multiplication) a number j is(=) 87.
j = unknown number/variable [So 17 plus 7j(7 times j) equals 87]
17 + 7j = 87
3.) n = number of calls
18 + 0.05n = 50.50
[Company charges $18 plus five cents per call(n), and the total charge was $50.50]
4.) s = the number of students
40 + 30s = 220
[Tutor charges $40 plus $30 per student(s), and the total charge was $220]
Answer: 11.775
If you plug in the radius (0.5 because the radius is half of the diameter) and the height to the formula for volume of a cylinder you will get pi•0.5 squared•15 which when solved is 11.775.
Last one and first. You can find out why by isolating the cube root and cubing both sides.
19 guests because each guest is $2 each according to the question.
