Let Grace have
[tex]g[/tex] number of stars, Then
Lenny will have half as many stars, That is, Lenny will have
[tex]\frac{1}{2}g[/tex] stars.
If Lenny collects 5 stars a day, then she will collect,
[tex]5 \times 7=35 [/tex] stars in a week.
Lenny will now have a total of
[tex]\frac{1}{2}g + 35 [/tex] stars.
Similarly,
If Grace collects 2 stars a day, then she will collect,
[tex]2 \times 7=14 [/tex] stars in a week.
Grace will now have a total of
[tex]g + 14 [/tex] stars.
After this one week Grace and Lenny now have the same number of stars.
[tex]\Rightarrow \frac{1}{2}g + 35=14+g [/tex]
