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:
Required solution (a) 
(b) 40.
Step-by-step explanation:
Given,
(a) Let,
Then,
Integrating 
we get,
Differentiate this with respect to y we get,
compairinfg with 
of the given function we get,
Then,
Again differentiate with respect to z we get,
on compairing we get,
(By integrating h'(z)) where C is integration constant. Hence,
(b) Next, to find the itegration,
Is that negative 2 minus 8? if so put that into the calculator and add 8 to both sides and divide by 2 after that. simple algebra
