69. The O'Brien's had $400.0 in a special checking account for installment payments.
After paying $40.00 a month for three months
and $20.00 a month for two months. How
much was left in the account?​

Hello :D

$40.00 x 3 = $120.00

$20.00 x 2 = $40.00

$120.00 + $40.00 = $160.00

$400.00 - $160.00 = $240.00

There is $240.00 left in the account.

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!