How do you fine the answer ? Help me pls

130

Step-by-step explanation:

120.

Step-by-step explanation:

Let the common difference be d. Then these equations are true,

so add all the left sides and all the right sides:

               y = 30-d

               x = 30-2d

               z = 30+d

               f = 30+2d

         y+x+z+f = 120

Notice that there are lots of different possibilities for x,y,z,f.

For example the arithmetic sequence could be  

10 20 30 40 50, which have sum 120 with d=10, or

20 25 30 35 40, which also have sum 120 with d=5, or  

54 42 30 18 6, which also have sum 120 with d=-12, or any of

an infinite number of possible arithmetic sequences.  But the

sum will always be 120.

b). 4320 have a nice day