Since we can't have half a tube, Jean will need to round up to the nearest whole number. Jean will need to use 5 tubes of glue to complete her plastic model.
To find out how many tubes of glue Jean will use to build her model, we can create an expression using the given fractions.
Let's start by determining how many tubes of glue are needed for one ounce. Since each tube contains 1/5 of an ounce of glue, we can represent this as 1 / (1/5) = 5 tubes of glue per ounce.
Next, we need to calculate the number of tubes required for 9/10 of an ounce. We can multiply the number of tubes per ounce (5) by the fraction 9/10:
5 * (9/10) = 45/10 = 4.5 tubes
The expression 5 * (9/10) represents the number of tubes of glue Jean will need to build her model. The solution to this expression is 4.5 tubes.