(x+ 14)y-xy= 1.96

14y= 1.96

y=0. 14

x(y+ 14)-xy=44

14x=44

x=22/7

2. let the middle number be x.

(x- 1)x(x+ 1)= 120 * 3x

x(x^2- 1)=360x

x^2=36 1

x= 19

These three numbers are 18 19 20.

3. set to b c d.

a+c=3b

(a+b+c+d)/4=2.6+b

(4b+d)/4=2.6+b

b+d/4=2.6+b

d= 10.4