You earned $13 on Monday and will earn more money tomorrow. , where d is the money you earn tomorrow, represents your total earnings for the two days.

Respuesta :

13+d=r
d = money you will earn tomorrow
r = money you earned in 2 darts

(you could use any 2 variables for the question, i just used r as an example)
13 + x = t, where “x” is the additional amount of money you earn and “t” being the total amount of your earnings.