hello :
let the equation : y = ax+b
xx-intercept (4.5,0) : 0 = a(4.5) +b .... (1)
yy-intercept (0,-5.4) .: - 5.4 = a(0)+ b .....(2)
by (2) : b = - 5.4
subsct in (1) : 4.5a -5.4 = 0
a = 5.4/4.5
a = 54/45
a = 6/5
the equation of the line (in slope intercept form) is : y =(6/5)x - 5.4