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.
5384=5000+384
4 * 5384 = 4(5000+384) = 4 * 5000 + 4 * 384
4 * 5000 = 20000
20000 + 4 * 384
So to find 5384 * 4, you add 20000 to 4*384. Less calculations