a student has $50 in saving and earns $40 per week. How long would it take them to save $450

a student has $50 in saving and earns $40 per week. How long would it take them to save $450

Set up the savings function S(w), where w is the number of weeks. The balance, S(w) is:
S(w) = Savings Per week * w + Initial Savings
S(w) = 40w + 50

The problems asks for how many weeks for S(w) = 450. So we have;
40w + 50 = 450

To solve for w, we type this equation in our search engine and we get:
w = 10