Question 59508
you can solve this problem numerically like this,

y=2x+1
when x=7, substitute the x value=7 in the given rule.
        y=2*7+1
         =14+1
         =15
That is when the input is 7, the output is 15.



To predict the output when input is 31/2,
for that, you just put the value x=31/2 in the given rule
that is,  y = 2 * 31/2 +1
           = 31 + 1= 32
That is when the inputis 31/2, the out put is 32