A truck can be rented from Company A for $130 a day plus $0.50 per mile. Company B charges $50 a day plus $0.70 per mile to rent the same truck. How many miles must be driven in a day to make the rental cost for Company A a better deal than Company B's?
For Company A to have a better deal, the truck must be driven more than miles per day

The charges of both companies will be same if truck is driven 200 miles per day

Company A will have better deal if truck is driven more than 200 miles per day ( because per mile rate of company A is less than company B

Step-by-step explanation:

Let the truck is driven X miles per day

Charges of company A will be = 90+0.4X

Charges of company B will be =30+0.7X

Let us find out value of X when charges of both companies are same

which means that   90+0.4 X= 30+0.7X

                            90-30      = 0.7X-0.4X

                            60    = 0.3X

                             60/0.3 = X

                             X= 200

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional