Explanation:
Let x be the number of households you mowed grass.
Let y be the number of households you shoveled snow.
From there, we know,

as equation 1.
next we also know,

as equation 2.
From here we know we can solve using simultaneous equations.
rearranging equation 1 with y the subject,

Substitute this equation into equation 2.

now substitute x = 14 into equation 1.

Therefore, you have mowed grass for 14 households and shovelled snow for 8 households.