Answer:
<em>He made 43 burgers.</em>
Step-by-step explanation:
Total amount of the ground beef
lb.
lb.
He used
of the beef to make tacos. So, <u>the amount of beef needed to make tacos</u>
lb.
The <u>amount of remaining beef</u>
lb.
So, <u>the amount of beef needed to make burgers</u>
lb.
Suppose, the number of quarter pound burgers 
So, the equation will be.....

Thus, he made 43 burgers.