We're diluting the first solution to make the second solution. This means both solutions will contain the same amount of H2SO4 (it's the concentration of it that changes). If you look at it this way, it's easy to find the unknown mass. Call this unknown mass m.
m * 0.875 = 275 g * 0.55 --> m = 173 g
What I'm saying here is 87.5% of the mass of the first solution needs to be the same as 55% of the mass of the second solution, because you're using the same amount of H2SO4 in both.
Please mark this brainliest!
