Please help me, I have trouble doing these type of questions.

Bettina= X(let)

Darren=3x

Jonathan=6x

120=X+3x+6x

X=12

so Bettina=12 yrs

Darren=36 yrs

Jonathan=72 yrs

Step-by-step explanation:

Let Bettina's age be B.

Then Darren's age is 3 times Bettina's, or 3B.

Jonathan's age is twice that of Darren, i.e. 2 (3B) = 6B.

Altogether, the sum of their age is

B + 3B + 6B  = 120 years

10 B = 120 years

B = 12 years.

Therefore

Bettina is 12 years old

Darren is 3 times as old as Bettina, so 36 years old.

Jonathan is twice that of Darren, so 72 years old.

Total = 72+36+12= 120 years, check!  :)

6 (3) - 4 + 32

hope this

since the airplane is moving with constant speed then the distance travelled can be calculated by x=u*t

in km/h would be:

x=640*3.5=2.240 km

in m/s would be:

u=640 km/h= 640.000 m/h =640.000/ 3600 m/s =177.8 m/s

t= 3.5 h= 3.5 * 3600 s=12.600 s

then x=u*t= 177.8*12.600= 2.240.280 m