Assuming you are hoping to obtain the value of "g", to solve worded algebra problems like these, it is easier to translate the world problem into a mathematical equation first.
In this case, "93 is the sum of a number g and 58" can be translated to:
93 = g + 58
To find the value of g, it is necessary to isolate g first. To do this, we subtract both sides of the equation by 58:
93 - 58 = g + 58 - 58
93 - 58 = g
Simplifying:
g = 35
