Hi there!
Here is how I would go about solving this problem:
Step 1: write the formula for percent yield.
Percent Yield= 100% x actual/ theoretical
Step 2: plug in known values and solve for theoretical yield.
29.5%= 100% x 157g/ theoretical
Rearrange the equation by multiplying theoretical out of the denominator. Divide 29.5% into the denominator-----> Theoretical= 100% x 157g/ 29.5%.
Theoretical= 15700g%/29.5%
Theoretical= 532g