8 x 9 = 72
So 72 is your answer
Solution:
we are given that
A student has some $1 and $5 bills in his wallet.
Let there x $1 bills and y number of $5 bills.
He has a total of 14 bills that are worth $34.
So we can write


Now solve these two equations together using substitution as follows

Hence there are 9 $1 bills and 5 bills are of $5.
Unit rate means how much does it cost for 1 unit
2.64 for 12 pencils
find 1 pencil
divide both sides by 12
0.22 for 1 pencil
0.22 per pencil
The answer should be 0.5x^4+12.5