Please help me finish this part of my study guide

(5,15)

Step-by-step explanation:

We know that 225 = 15a + 10c, and he purchased a total of 20 tickets, so

a + c = 20, using this, we know that c = 20 - a, we can substitute this for c in 225 = 15a + 10c to get:

225 = 15a + 10(20 - a) =

225 = 15a + 200 - 10a

225 = 5a + 200

25 = 5a

a = 5

Now we substitute 5 for a:

225 = 15a + 10c

225 = 15(5) + 10c

225 = 75 + 10c

150 = 10c

c = 15

so a = 5 and c = 15, the solution is (5,15)

P.S. I'm the guy who did your other question

x= -3 and

step-by-step explanation:

to find the roots of a cubic, use division or factoring to find the factors then set equal to 0. as this is a difference of cubes, it factors into

where a is the cube root of .

here   this is 27 and the cube root of 27 is 3. so we write using the form:

.

set each factor to 0 and solve for x.

x-3=0

x=3

the quadratic expression does not factor and must be solved using the quadratic formula.

where a = 1, b=3, and c=9

this cubic has two complex roots.

answer: the anser is 3

step-by-step explanation:

c- 2o is equal to 9