$1-(4$pts$)$ An optimization model must decide how to allocate available supplies at sources

to meet requirements at customers $.$ Using decision at variables

amount allocated from source i to customer j

formulate each of the following requirements$($constraints$)$ in a single line $($hint: use summation

sign, for all$/$each notation where necessary$).$

a$.$ The amount allocated from sources $25$ cannot exceed the supply available at $25.$

b$.$ The amount allocated from each source i cannot exceed the supply available at i$.$

c$.$ The amount allocated to customer n from sources $1$ and $2$ should equal half the requirement

at n$.$

d$.$ The amount allocated to each customer j should equal the requirement at j$.$