Need help with number 2 pls

1h> 70x3=210 bacteria

2h> 210*3=630 bactaeria

let be y the number of bacteria at the t=0h

it is y=70 3^0

for t= 1h

y=70*3^1=210

for t=2h

y=70*3^2=630

so we can write y=70*3^x, where x is the number of hour