Final answer:
The equation E = 50a + 125 represents the situation where E is the amount earned and a is the number of memberships sold.
Step-by-step explanation:
The equation that represents the situation is E = 50a + 125.
Here, E represents the amount earned and a represents the number of memberships sold. The equation E = 50a + 125 shows that the amount earned is $50 per membership sold, plus an additional $125.
For example, if Mr. Singh sells 5 memberships, the equation would be E = 50 * 5 + 125, which equals $375 earned. If he sells 8 memberships, the equation would be E = 50 * 8 + 125, which equals $525 earned.