Answer:
a = 15 , b =

Explanation:
the equation of proportion is
y = kx ← k is the constant of proportion
to find k substitute x = 0.7, y = 2.1 , values from the table into the equation
2.1 = 0.7k ( divide both sides by 0.7 )
3 = k
y = 3x ← equation of proportionality
then using x = 5
a = 3 × 5 = 15
using y =

= 3b ( multiply both sides by 3 to clear the fraction )
2 = 9b ( divide both sides by 9 )
= b