Find the test statistic z for the following situation Claim

Find the test statistic, z, for the following situation: Claim: p_1

p = (p₁ * n₁ + p₂ * n₂) / (n₁ + n₂) = ( 140+ 255) / ( 200 + 340) = 0.7314815....
std. error = sqrt{ p * ( 1 - p ) * [ (1/n₁) + (1/n₂) ] = sqrt( 0.7314815*( 1 - 0.7314815)*( ( 1/200)+( 1/340) )
= 0.03949401.......

Test statistic = [ ( 140 / 200) - ( 255 /340) ] / 0.03949401 = -1.266015......

p-value = 0.1030278 d.f = 340+200 -2 = 538....