4. a A dealer made a profit of \( 22 \frac{1}{2} \% \) by selling a car for GHC \( 5,880.00 \). Find the percentage profit he would have realized if he had sold it for GHC \( 6,120.00 .2 \mathrm{~cm} \) to 2 km on the distance axis. b. The sum of four consecutive even numbers is 28 . Find the numbers. c. Solve the following system of linear equations in two variables using the elimination method. \( x+y=1 x+y=1 x+y=1 \) and \( x-y=3 x-y=3 x-y=3 \).

To find the percentage profit if the car was sold for GHC 6,120.00, we first need to determine the cost price (CP). If a profit of \( 22 \frac{1}{2} \% \) is earned on a selling price (SP) of GHC 5,880.00, we can express this as \( SP = CP + (22.5\% \text{ of } CP) \). By solving this, we find the CP is GHC 4,800.00. If sold for GHC 6,120.00, the profit is GHC 6,120.00 - GHC 4,800.00 = GHC 1,320.00. The profit percentage is then \( \left( \frac{1,320}{4,800} \times 100 \right) \approx 27.5\% \). Now, on to finding those consecutive even numbers! Let's denote those four consecutive even numbers as \( x, x+2, x+4, x+6 \). Together they add up to 28, which gives us \( x + (x+2) + (x+4) + (x+6) = 28 \). Simplifying that yields \( 4x + 12 = 28 \). Therefore, \( 4x = 16 \) and \( x = 4 \). Thus, the numbers are 4, 6, 8, and 10. Easy peasy! For the system of equations given, actually, you've repeated the equation \( x + y = 1 \) three times, which doesn't affect solving. The second equation \( x - y = 3 \) is valid. From \( x + y = 1 \), we can express \( y = 1 - x \). Substituting into \( x - y = 3 \) gives \( x - (1 - x) = 3 \) or \( 2x - 1 = 3 \). Solving this, we find \( x = 2 \) and substituting back to find \( y = 1 - 2 = -1 \). So the solution to the system is \( (2, -1) \)!