I’m pretty sure that it’s smth like this
Z = (X - mean)/sd
-1 = (28 - mean)/sd
mean - sd = 28 . . . (1)
-0.5 = (34 - mean)/sd
mean - 0.5sd = 34 . . . (2)
(1) - (2) => -0.5sd = -6
sd = -6/-0.5 = 12
From (1), mean = sd + 28 = 12 + 28 = 40
mean = 40
standard deviation = 12
Multiplying by 2 and then adding 10 145*2=290+10=300
300*2=600+10=610
610*2=1220 + 10=1230
x=2 y=10
x+y=12
Distribute : 1/2x + 3 = 18
subtract the 3 from both sides: 1/2x= 15
divide: x= 30
