tolong ya kak pleas!!!

86 + 87 + 92 + x / 4 = 90
86 + 87 + 92 + x = 90 × 4
265 + x = 360
x = 360 - 265
x = 95
nilai ujian yg keempat adalah 95

Nilai rata-rata
= 86 + 87 + 92 + (Nilai yg hrs dicapai) ÷ 4
= 265 + (Nilai yg hrs dicapai) ÷ 4

Nilai rata ratanya kan 90, jadinya
90 = 265 + (Nilai yg hrs dicapai) ÷ 4
90 × 4 = 265 + (Nilai yg hrs dicapai)
360 = 265 + (Nilai yg hrs dicapai)
Nilai yg hrs dicapai = 360 - 265
Nilai yg hrs dicapai = 95