"in an equal amount" is correct and usable in written English.
You can use it when you want to say that two or more things are equal to each other. For example: "She and her friend each received in an equal amount of money for their work."
But we put in an equal amount into Stormwind in terms of artist time.
His group is calling for the city and counties to contribute $65 million, and the state to pitch in an equal amount.
A clothing manufacturer, named Julius Rosenwald, invested $25,000, and his brother-in-law, Aaron Nusbaum put in an equal amount.
The prime minister's spokesman declined to say what the gift might be, although the BBC reported that ministers all chipped in an equal amount.
Where life expectancy has increased by 18 years in an equal amount of time, where the offensive smell of cigarettes no longer remains, where the food is good and the people friendly.
(By the way, a batch of simple syrup, made by stirring sugar in an equal amount of water until it dissolves, is a handy thing to keep around in hot weather).
The first Gates grant for immunization, for instance, resulted in roughly an equal amount pledged from other donors, mostly governments.
Do you find that among international students in particular an equal amount of girls apply and are admitted to American universities as boys?
In addition, an equal amount of a mixture containing all of the samples types was labeled with TMT-131 as an internal control for quantification.
In parallel, an equal amount of cells was cultured without the growth factors.
Therefore, an inhibition experiment was performed in which an equal amount of each antibody was added to the BoNT/A Endopep-MS reaction.
