The sum of twice a number x and one-half the number is 30

2x  +1/2x = 30

2 1/2x = 30

x = 30 / 2 1/2 = 12

check:

2(12) + 1/2(12) = 24+6 = 30 = True

 the number is 12

i only know the sequence of arithmetic it adds the first is 5+4 then it goes up as it adds to then it is 9+5 then 14+6 then to 20+7 and so on. 5,9,14,20,27,35.

step-by-step explanation:

sounds & other waves originate from any vibrating object