I think you have the area and length swapped if that's true, continue:
3.125 divided by 2.75 is 1.13(continues on with 36 repeating) this means that 1.13 Feet is the width because you basically take the equation backwards: L*W=A therefore, A/L=W or A/W=L
A = L * W 2 3/4 = 3 1/8 * W Change to improper fractions. 11/4 = 25/8 * W Multiply both sides by the reciprocal of 25/8 (8/25) to clear the fraction with the W. (8/25)(11/4) = W 88/100 = W 22/25 = W OR 0.88ft