Answer:
[tex]x = 4\\y = 9[/tex] hours
Step-by-step explanation:
Given -
x represents the number of hours lifeguarding and y represents the number of hours landscaping
[tex]x+ y = 13[/tex] -----Eq ( 1 )
and
[tex]20 * x + 10 * y = 170[/tex] -----Eq ( 2 )
Substituting the value of [tex]x = 13-y[/tex] in equation 2, we get -
[tex]20* (13 - y) + 10 y = 170[/tex]
[tex]260 - 20 y + 10 y = 170\\10y = 90\\y = 9[/tex]
[tex]x = 13-9 = 4[/tex]