In any equation always multiplication has to be considered first, then we can add or substract the rest. 1) First "b" value multiply with "x" value afterwards (+) or (- )"a" value 2) Equation y= a+bx 3) 90+2(-3) here a=90, b=2, x= -3 4) 90-6 (bx = b into x is +(2×-3)=-6) 2 into 3 = 6 and ( plus into minus is minus) which is +2×-3 = -6 5) 90-6=84
For Trend value of 2007= 90+2(-3) Here the number in the bracket should be multiplied by number outside the bracket which is 2×3=6, and also multiply (+) and (-) = (-)because plus x minus = minus, so answer is 90-6 which is equal to 84, hope u understand