Tolong dengan caranya

38 = { ( 5 × 36 ) + ( 10 × 37 ) + ( 10 × 38 ) + ( x × 39 ) + ( 5 × 40 ) } / ( 5 + 10 + 10 + x + 5 )

38 = ( 180 + 370 + 380 + 39x + 200 ) / ( 30 + x )

38 ( 30 + x ) = 1130 + 39x

1140 + 38x = 1130 + 39x

1140 - 1130 = 39x - 38x

10 = x

jadi nilai x = 10