Given the expression:
13 + w/7 = -18
Step 1: First thing is to find the LCM of the expression at the left hand side as shown:
[13(7)+w]/7 = -18
(91+w)/7 = -18
Step 2: Cross multiply from here:
91+w = -18 * 7
91+w = -126
Step 3: Subtract 91 from both sides:
91+w-91 = -126-91
Step 4: Calculate the value of w:
w = -126-91
w = -217
Hence the value of w is -217