It really is not at all different, except the format.
Examing it —
syms p
A=0.1199;
At=0.112;
y=1.43;
P1=119;
Error =0.01123;
eqn= ((At^2)/(A^2))==(((y+1)/2)^((y+1)/(y-1)))*(2/(y-1))*(((p/P1)^(2/y))-((p/P1)^(y+1/y)))
solve( eqn,p )
Different format, however same value —
LHS_eqn = lhs(eqn)
LHS_eqn_dec = vpa(LHS_eqn)
At_squared = At^2
A_squared = A^2
LHS_frac = At_squared / A_squared
LHS_dec = vpa(LHS_frac)
.