The correct answer is:
Let y be the total change in Jabari's shares. There are 4 weeks in a month; this means the equation would be: y = (-1m + 0.45n)4 = -4m + 1.8n.
Step-by-step explanation:
Jabari has 100 shares of Stock A, and it decreased by m cents per share per week. We represent the fact that it decreased by m cents instead of dollars as 0.01m, since 1 cent is 0.01 dollars. Since there are 100 shares, we multiply this by 100: 100(0.01m) = 1m. Since the value decreases, this is -1m.
He has 45 shares of Stock B, and it increased by n cents per share per week. We represent the fact that it decreased by n cents instead of dollars as 0.01n, since 1 cent is 0.01 dollars. Since there are 45 shares, we multiply this by 45: 45(0.01n) = 0.45n. Since the value increases, this is positive 0.45n.
Together, this gives us a change for one week of -1m+0.45n. However, we are looking at a month, which has 4 weeks. This means we multiply this by 4:
y = (-1m + 0.45n)(4)
Using the distributive property,
y = -1m(4) + 0.45n(4)
y = -4m + 1.8n