Nickels are 5 cents, and dimes are 10 cents.
(By luck..) eventually you can have 12 dimes, meaning you have 120 cents, or $1.20 ... 20-12=8.. meaning you used 12 dimes and are missing 8 more coins. which means you can have 8 nickels which is 40 cents. 120+40=160 cents or $1.60
Hope this helped.
Answer: 10 + 7x
40
We can use exclusion method:
A and C is not correct because Ms Hernandez doesn't want to spend more than 40 dollars --> so it must be less than or equal to 40