Tolong dibantu kak, sambil belajar juga, yang a sama yang b

Tolong dibantu kak, sambil belajar juga, yang a sama yang b

$sumlimits^{20}_{n = 1} : (2p_{n} - 3) = 120$

$equiv 2sumlimits^{20}_{n = 1} : p_{n} - sumlimits^{20}_{n = 1} : 3 = 120$

$equiv 2sumlimits^{20}_{n = 1} : p_{n} - (3 times 20) = 120$

$equiv 2sumlimits^{20}_{n = 1} : p_{n} = 120 + 60 = 180$

$equiv sumlimits^{20}_{n = 1} : p_{n} = 180 : 2$

$boxed{ boxed{ equiv sumlimits^{20}_{n = 1} : p_{n} = 90}}$

$sumlimits^{20}_{n = 1} : (3p_{n} + 4) = 3sumlimits^{20}_{n = 1} : p_{n} + sumlimits^{20}_{n = 1} 4$

$sumlimits^{20}_{n = 1} : (3p_{n} + 4) = (3 times 90) + (4 times 20)$

$sumlimits^{20}_{n = 1} : (3p_{n} + 4) = 270 + 80$

$boxed{ boxed{sumlimits^{20}_{n = 1} : (3p_{n} + 4) = 350}}$