31.) you decide to market your own custom computer software. you must invest $3,255 for computer hardware, and spend $2.90 to buy and package each disk. if each program sells for $13.75, how many copies must you sell to break even?

a.) 301 copies

b.) 300 copies

c.) 195 copies

d.) 196 copies

B. 300 Copies

Step-by-step explanation:

So inplace of the copies you input the value x. Then, create an equation...

3,255= 13.75x -2.90x

3,255= 10.85x

Next you have to isolate x

3,255/10.85 = 300

so, 300=x

Number of dimes: x
Number of quarters:  x + 3

B ) 0.10 x + 0.25 ( x + 3 ) = $1.80
Also we can solve this equation:
0.10 x + 0.25 x + 0.75 = 1.80
0.35 x = 1.80 - 0.75
0.35 x = 1.05
x = 1.05 : 0.35
x = 3,  x  + 3 = 6
He has 6 quarters and 3 dimes. 
( 6 * 0.25 + 3 * 0.10 = 1.50 + 0.30 = $1.80 - correct)