A mixture of 10.00 mL of H2SO4 and 30.00 mL of HCl required 20.00 mL of 2.500 M NaOH

Question

for complete reaction. When 30.00 mL of H2SO4 and 10.00 mL of HCl were used,
28.00 mL of 2.500 M NaOH were required. What were the concentrations of the acids?
[Both were 1.000 M]
H2SO4(aq) + 2NaOH(aq) Na2SO4(aq) + 2H2O(l)
HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)

Answer 1

Let x = M H2SO4
and y = M NaOH
(Note that it takes 2 mols NaOH to react with 1 mol H2SO4.)
In words;
eqn 1: mols H2SO4 + mols HCl = mols NaOH
eqn 2: mols H2SO4 + mols HCl = mols NaOH
Change word equation to numbers.
10x*2 + 30y = 2.5*20 is eqn 1.
30x*2 + 10y = 2.5*28 is eqn 2.

Solve the two equations simultaneously for x and y.