Chemistry help please?

A beaker with 175 ml of an acetic acid buffer with a pH of 5.00 is sitting on a benchtop. The total molarity of acid and conjugate base in this buffer is 0.100M . A student adds 6.90 mL of a 0.340 M HCL solution to the beaker. How much will the pH change? The pKa of acetic acid is 4.760.



Basically whats delta pH?Chemistry help please?
let y = [acetate]

let x = [acetic acid]



5.00 = 4.760 + log y/x

10^0.24 = 1.74 = y/x

1.74 x = y

but we know that y + x =0.100



1.74 x = 0.100-x

x = 0.0365 M

y = 0.0635 M

moles acetic acid = 0.0365 x 0.175 L= 0.00639

moles acetate = 0.0635 x 0.175 L= 0.0111

moles H+ added = 6.90 x 10^-3 L x 0.340 M= 0.00235

CH3COO- + H+ = CH3COOH

moles acetate = 0.0111 - 0.00235 = 0.00875

moles acetic acid = 0.00639 + 0.00235 = 0.00874

pH = 4.760 + log 0.00875 / 0.00874 = 4.76



delta pH = 5.00 - 4.76=0.24