What is the solution of (0.5x-y=1.5) and (x+0.25y=7)?

Correct answer: (x=59/9, y=16/9)

Multiplying the first equation by 2 and the second by 4 removes the decimals, giving x-2y=3 and 4x+y=28. Multiply the first of these by 2 and add it to the second equation: 9x=59, so x=59/9. Substituting this into x-2y=3 gives y=16/9. Therefore, the solution is (59/9, 16/9). For example, option B satisfies the first equation, but in the second equation it gives 6+0.25(3/2)=6.375, not 7. Exam tip: When coefficients are decimals, first convert the equations to integer coefficients and then verify the final pair in both original equations.