we are told that Sylvia needs $110 and that she already has $16, therefore, the amount she needs to complete the $110 is the difference, that is:
Since she works 10 hours and "h" are the hourly earnings then the product of the number of hours by the hourly earnings must be equal to the amount she needs to complete, that is:
Therefore, equation 1 can be used. We can also add 16 to both sides and we get:
Therefore, equation 4 also can be used.