Jamel uses the two equations to solve the system algebraically. Since both equations start with h=, he can set the expressions 18 - s and 12.5 - 0.5s equal to one another.

`h = 18 - s `

`h = 12.5 - 0.5s`

`18 - s= 12.5 - 0.5s`

Then use one of the original equations and replace s with number of shirts to find the